The advent of field-installable accessories for use within industrial-rated circuit breakers has fostered the increased use of such accessories to provide remote indication of the operating conditions of related electrical equipment as well as providing means for turning such equipment ON and OFF from a remote location. U.S. Pat. No. 4,754,247 entitled "Molded Case Circuit Breaker Accessory Enclosure" describes an industrial-rated circuit breaker that includes an accessory door for facilitating the field-installation of selected accessory units within the circuit breaker cover.
U.S. Pat. No. 4,757,294 entitled "Combined Trip Unit and Accessory Module for Electronic Trip Circuit Breakers" describes a combined trip actuator mechanism and accessory unit for articulating the circuit breaker operating mechanism and interfacing with the accessory unit for remote trip as well as trip indication function.
U.S. Pat. No. 4,794,356 entitled "Molded Case Circuit Breaker Auxiliary Switch Unit" describes an auxiliary switch unit that is mounted in the circuit breaker cover and interacts with the circuit breaker operating mechanism to provide remote trip indication.
With higher-rated circuit breakers used with industrial equipment rated up to 1200 amperes continuous current, for example, a so-called "flux shifter", actuator device is required to articulate the powerful operating mechanism springs that are required with the heavier current-carrying components within the circuit breaker assembly.
U.S. Pat. No. 3,693,122 discloses one such flux transfer trip device for electronic trip units wherein the flux provided by a permanent magnet is opposed by a magneto-motive force produced by a solenoid winding. A flux diverter interposed between the permanent magnet and the spring-based tripping armature provides instantaneous trip properties by effectively de-coupling the permanent magnet flux upon operation of the solenoid winding.
When a flux shifter-trip actuator device is used in combination with an auxiliary device such as a bell alarm or auxiliary switch, for example, an interface unit is required for providing mechanical logic to the flux shifter unit, the auxiliary device and the circuit breaker operating mechanism to ensure that the operating mechanism responds to interrupt the circuit current while the auxiliary device reacts at the same time to provide remote visual indication of such interruption event. When such higher-rated circuit interrupters include separate main and arcing contacts whereby the main contacts separate before the arc occurs between the arcing contacts some means must be used to promote the transfer of the arc away from the arcing contacts.
Accordingly, one purpose of the invention is to provide a multi-functional actuator-reset unit to ensure that the operating mechanism freely responds to overcurrent conditions while such response is indicated via an auxiliary device. The actuator-reset unit also provides reset function to the flux shifter unit immediately following the overcurrent event.
Another purpose of the invention is to promote the transfer of the arc away from the arcing contacts upon contact separation under intense overcurrent conditions.